Rate actuator for hydraulic rate controlled systems



June 4, 1968 w, BQQTHROYD 3,386,293

RATE ACTUATOR FOR HYDRAULIC RATE CONTROLLED SYSTEMS Filed Dec. 2, 1964 INVENTOR HOWARD w. BOOTHROY'D B) r @f ATTORNEY United States Patent Office 3,385,293 Patented June 4, 1968 3,386,293 RATE ACTUATOR FOR HYDRAULIC RATE CONTROLLED SYSTEMS Howard W. Boothroyd, Amherst, N.H., assignor to Sanders Associates, Inc, Nashua, NJbL, a corporation of Delaware Filed Dec. 2, 1964, Ser. No. 415,528 17 Claims. (Cl. 74-16) This invention relates to a rate actuator, and more particularly, for such an actuator especially useful in hydraulic rate-controlled systems, such as those employed in navigation systems for operation of the roll, pitch and yaw controls, as one example.

In systems of the type in which the present invention may be employed, employing a separate rate gyroscope, servo valves, amplifiers and an actuator, the electrical transducers in the gyro and servo valves are all sources of possible error signals, such as noise pulses, and null shifts, and these errors may be costly in terms of faulty operation of the system.

The present invention eliminates the electronic pick-off and force motor, providing more nearly error-free and less costly operation. It embodies a direct input to the first stage of the valve, and a torque generator 'which is also available for summing other data to provide independent electrical input control of the rate actuator by an external electrical signal.

From the foregoing, it will be understood that among the objects of this invention are:

To provide an improved rate actuator for use in hydraulic systems,

To eliminate the electrical pick-oft and force motor heretofore employed in such systems,

To eliminate the costly error signals heretofore generated in the electrical transducers in the gyro and servo valve, such as noise pulses and null shift,

To provide a sensed rate which is a direct input to the first stage of the servo valve,

To provide a torque generator in the system, which generator is also available for summing other data to provide independent electrical input to the rate actuator,

To provide direct coupling of a sensed rate indicator to drive the first stage of a servo valve, also having provision for external control by independent electrical signal, such as a rotary force motor or torquer.

The features of novelty which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its fundamental principles and as to its particular embodiments, will best be understood by reference to the specification and accompanying drawing, in which FIG. 1 is a cross-sectional elevation of a rate actuator according to this invention, taken on lines 1--1 of FIG. 2 in a plane perpendicular to the precession axis of the gyro embodied therein, and

FIG. 2 is a similar view taken on lines 22 of FIG. 1, in the plane of the precession axis.

Referring now more particularly to FIG. 1, designates a hollow casing having within it a generally cylindrical chamber in which the rotary piston is arranged for partial rotation, of the order of 10, either clockwise or counterclockwise about the null position shown in FIG. 1.

The rotary piston is provided with a plurality of radially and longitudinally extending segments or teeth 16, 17, 18 and 19 which, together with inwardly extending segments or teeth 16a, 16b and 160 on casing 10, control the flow of hydraulic fluid. The actuator is provided with a pressure conduit 11, connected to the pressure side of the hydraulic system by which hydraulic fluid flows into the casing 10 and chamber 11a with branches 11b and to chambers 20 and 21 and with return conduits 12a and 12b from chambers 12c and 12d, respectively, within piston 15.

From conduit 11, branch conduits 11b and 110 lead to compartments or chambers 20 and 21 (P V and P V respectively, and from these chambers conduits 24 and 25 lead to nozzles 24a and 25a, respectively, the jets from which impinge on opposite sides of an extension 26a projecting from gimbal 26 within casing 10. From the foregoing, it will be seen that the net force applied by the jets from nozzles 24a and 25a is proportional to the pressure dilference P V P V and, because of the reversed positioning of the nozzles, this force opposes the original movement of the rotary piston, derived in a manner to be described, from the input signal.

When the torque induced by counterclockwise rotation of the rotary piston equals the signal torque, the rotary piston is in stable equilibrium, pressure P V =P V and the valve action of the rotary piston segment 18 permits fluid to flow from pressure conduit 11 through chamber 11a into chamber 12c and line 14 (C At the same time, counterclockwise movement of segment 17 opens hydraulic line 13 (C to pressure return line 12b. The flow of hydraulic fluid into line 14 (C and out of return line 12b actuates the pressure actuated valves supplied by line line 14 (C for example, may swing a ships rudder through a predetermined angle away from amidship in one direction. When the rotary piston has attained a position of equilibrium, the flow of hydraulic fluid through line 14 (C is then a function of the input rate or signal, ant, as long as the rate remains constant, the C flow also remains constant. It will be noted that for any movement of piston 15 away from null or center position, the volumes in chambers 20 and 21 vary inversely with each other.

If the sign of the input rate or signal is opposite, as for a turn in the opposite direction, the rotary piston moves clockwise from null position, and the action is similar but interchanged. In this instance, the piston connects pressure line 11 and chamber 11a through chamber 12d to line 13 (C and vents line 14 (C through chamber to return line 1211. In this instance return line 12b is closed by segment 17; in the former, return line 12a was closed by segment 18.

Turning now to FIG. 2, in addition to the gyro rotor 22 mounted on shaft 23 in gimbal 26, casing 10 contains a preferably hollow torsion bar support 40 for gimbal 26, extending longitudinally of said casing, and carrying, at its left hand end, the rotor 30r of a torque generator 30, the stator 30s of which surrounds the rotor 30r, and is fixed to the inside of casing 10. The rotary piston 15, which is hollow, preferably surrounds the gyro and gimbal assembly, except for extension or bafile 26a, which projects downwardly through an opening 10c into chamber 10b in an extension 10a of the casing 10, where it is impinged on by jets from nozzles 24a and 25a.

Rotary piston 15 is mounted for rotation in casing 10 in end bearing 36 and 37. Gimbal torsion bar support 40 is held by null adjusting screw 43, and lock nut 44. The opposite end of the gimbal carries torsion reference spring 46, which is connected to S spring 48 by means of hub 31, the outer ends of which are secured to a ring 49 positioned on the inside of rotary piston 15 (as shown in FIG. 2). Electrical connections may be brought into casing 10 by cable 52 passing through a suitable opening 53, primarily to energize the torque generator by an ex ternal signal or signals.

With the construction of the rate actuator, as explained, it is assumed that normal supply pressure P exists in the hydraulic system, that the rate input is zero (no signal is being generated), and the unit is in null condi- 3 tion, with the rotary piston 15 in the position shown in FIG. 1, and pressure P V =P V Let the unit be subjected to an angular velocity (turn) about the input axis. The gyro element responds by a precession, moving the gimbal and rotary piston in the di rection of arrow A in FIG. 1 about the output axis, which is perpendicular to the input axis. This action induces a torque in the torsional reference spring 46 and torsion bar support 40, and this is accompanied by the development of a pressure difference in chambers P V and P V because of the gimbal and battle, 26a, displacement from null position.

This pressure difference tends to drive the rota y piston 15 in a direction opposite to the first (original) motion of the gimbal and creates an additional torque in the torsion bar support and torsional reference spring. When the torque resulting from the motion of the rotary piston equals the original signal torque, the rotary piston becomes stationary, pressure P V =P V and the valve ports fluid through C and allows fluid from C to return. The C fluid flow is then a function of the input rate (signal), and, as long as the rate remains constant, fluid flow through C remains constant.

Assume now the rate input is reduced to Zero. The torque in direction A becomes zero, and, because the torque in the torsion bar support always counteracts the gimbal precessional torque, it again predominates when the precessional torque in direction A drops to zero. This torque now acts to rotate the gimbal in direction D, which in turn upsets the pressure P V P V balance and causes the rotary piston to rotate in direction D until null position is reached and both lines C and C, are closed.

Many variations of. the invention shown and described may be made. To mention only a few, as examples, and not in limitation, it may be used without the gyroscopic rotor as an electro-hydraulic torquer operated servo valve, be employed as a modified Sanders Associates valve by simply replacing the conventional force (torque motor) with a "imballed gyro, and may exist with or without a rotary or linear actuator attached. In the drawing 1 have shown it with an attached rotary actuator 50, with its output shaft 51 parallel to the output axis.

In the foregoing, I have shown and described certain preferred embodiments of my invention, and the best mode presently known to me, of practicing the same, but it will be understood that modifications and changes may be made without departing from the spirit and scope or" my invention, as will be clear to those skilled in the art.

I claim:

1. In a rate actuator for hydraulic systems, in combination, a casing having ports and chambers for hydraulic fluid flow, a rate gyro mounted in a gimbal in said casing, means including said gimbal for operatively connecting said gyro to a rotary piston, said rotary piston having segments arranged to control the flow of fluid through said ports, and means associated with said gimbal for applying a torque thereto opposed to the precessional torque produced by said gyro in response to movement of said gyro about its input axis.

2. in a rate actuator for hydraulic systems, in combination, a hollow casing having ports and chambers for hydraulic fluid flow, a rate gyro mounted in a gimbal in said casing, means including said gimbal for operatively connecting said gyro to a rotary piston, said rotary piston coaxial with said gimbal, said piston having portions controlling the flow of fluid through said ports, and a torsion bar supporting said gimbal and applying a torque thereto opposing the precessional torque produced by said gyro in response to movement of said gyro about its input axis.

3. In a rate actuator for hydraulic systems, in combination, a hollow casing having ports and chambers for hydraulic fluid flow, a rate gyro mounted in a ginibal having an extension mounted in said casing, means responsive to movement of said gyro to control the flow of fluid through said ports and chambers, and means for applying fluid jets in opposite directions to said extension to cause said control means to return to its null position.

i. The combination claimed in claim 3 with a pair of fluid nozzles directing jets of fluid against said extension, one of said jets aiding precession torque on said gimbal, and the other opposing it.

5. In a rate actuator for hydraulic systems, in combination, a hollow casing having ports and chambers for hydraulic fluid flow, a rate gyro mounted in a gimbal having an extension mounted in said casing, means responsive to movement of said gyro to control the flow of fluid through said ports and chambers, and means for applying to said extension a pair of fluid jets in opposite directions to produce a force on said extension proportional to the difference of pressure times volume in two of said chamhers respectively, to cause said control means to return to its null position.

6. In a rate actuator for hydraulic systems, in combination, a hollow casing having ports and chambers for hydraulic fluid flow, a rate gyro mounted in a gimbal, said gyro being responsive to movement thereof about its input axis, and means including a rotary piston controlling the fluid flow to said system as a function of the movement of said gyro about its input axis.

7. In a rate actuator for hydraulic systems, in combination, a casing having ports and chambers for hydraulic fluid flow, a rate gyro mounted in a gimbal, said gyro being precessionally responsive to movement thereof about its input axis, and means including a rotary piston cooperating with said casing for controlling the fluid flow to said system as a function of the movement of said gyro about its input axis, said means including both resilient and a non-resilient means for opposing the precession torque of said gyro.

8. The combination claimed in claim 7, in which said resilient means includes a torsion bar, and said non-resilient means includes a pair of jet nozzles for directing fluid jets at a portion of said gimbal.

9. The combination claimed in claim 7, in which said resilient means includes a torsion bar, and said non-resilient means includes means for producing fluid jets impinging on said gimbal, the net force of said jets being proportional to the pressure times volume difference between fluid in a pair of chambers in said housing.

It). In a rate actuator for hydraulic systems, in combination, a hollow casing having ports and chambers for controlling the flow of hydraulic fluid, a rate gyro mounted in a gimbal in said casing, means including said gimbal for operatively connecting said gyro to a hollow rotary piston, said hollow rotary piston surrounding said gimbal, said piston having segments arranged to close and open ports in said casing, a resiliently centered support for said gimbal, and a torque generator carried by said gimbal and said casing.

11. The combination claimed in claim It) with means extending out of said casing for impressing signals from an external source on said torque generator.

12. The combination claimed in claim 10 with null adjusting means for said gimbal carried on said casing.

13. The combination claimed in claim 12 in which said torque generator is located on the rotational axis of said gimbal between said gyro and said null adjusting means.

14. In a rate actuator for hydraulic systems, in combination, a casing having ports and chambers for hydraulic fluid flow, a rate gyro mounted in a rotary gimbal, said gyro being precessionally responsive to movement thereof about its input axis, a rotary piston valve driven by the precession or" said gyro, and means for opposing rotation of said gimbal, said last means operating with a force proportional to P V P V where P and V are respectively pressure and volume of fluid in a first chamber in said casing, and P and V are pressure and volume of fluid in a second chamber, and where V and V vary inversely with each other.

15. The combination claimed in claim 7, in which said resilient means includes a torsion bar supporting one end of said gimbal, and a torsional reference spring secured to the other end of said gimbal.

16. The combination claimed in claim 7, in which said resilient means includes a torsion bar supporting one end of said gimbal, a torsion reference spring secured at one end to the other end of said gimbal and at the other end to an S spring secured to said rotary piston within said casing.

171 In a rate actuator for hydraulic systems in combination, a hollow casing having ports and chambers for controlling the flow of hydraulic fluid, a rate gyro mounted in a gimbal in said casing, a hollow rotary piston surrounding said gimbal, said piston and said casing having outwardly and inwardly projecting longitudinal teeth, respectively, providing porting of fluid, means comprising a torsion bar and a torsional reference spring secured to opposite ends of said gimbal, the other end of said torsion bar being connected to said casing, and the other end of said torsional reference spring being connected to said rotary piston.

References Cited UNITED STATES PATENTS 1,592,081 7/1926 Colvin 745.6 X 2,584,125 2/1952 Haglund 745.6 2,754,789 7/ 1956 Minisini 74-5.6 2,852,942 9/1958 Gerard 745.6 2,865,205 12/1958 Lear 745 C. J. HUSAR, Primary Examiner.

FRED C. MATTERN, Examiner.

I. PUFFER, Assistant Examiner. 

1. IN A RATE ACTUATOR FOR HYDRAULIC SYSTEMS, IN COMBINATION, A CASING HAVING PORTS AND CHAMBERS FOR HYDRAULIC FLUID FLOW, A RATE GYRO MOUNTED IN A GIMBAL IN SAID CASING, MEANS INCLUDING SAID GIMBAL FOR OPERATIVELY CONNECTING SAID GYRO TO A ROTARY PISTON, SAID ROTARY PISTON HAVING SEGMENTS ARRANGED TO CONTROL THE FLOW OF FLUID THROUGH SAID PORTS, AND MEANS ASSOCIATED WITH SAID GIMBAL FOR APPLYING A TORQUE THERETO OPPOSED TO THE PRECESSIONAL TORQUE 